Veterans (age 60-80 yrs, N=12) be randomized in a double-blind placebo-controlled fashion to consume supplement or placebo for four weeks. After two weeks of consumption, subjects will be treated with a vaccine for tetanus, diphtheria, and pertussis. Blood will be drawn from each subject before and after vaccination to determine the effects of the supplement on immune response to vaccination. Additionally, subjects will undergo blood draw and muscle biopsy before and after two weeks of supplementation to determine the effects of supplementation on other measures of immune function (e.g. cytokine and growth factor levels). This is an important issue due to the serious health consequences associated with muscle loss in older adults and the need for improved strategies for rehabilitation.